From df085f1cb3acd3d75408ff94f366983873bce7d2 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@decadent.org.uk>
Date: Sun, 1 Nov 2015 16:22:53 +0000
Subject: [PATCH] ppp, slip: Validate VJ compression slot parameters completely
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commit 4ab42d78e37a294ac7bc56901d563c642e03c4ae upstream.

Currently slhc_init() treats out-of-range values of rslots and tslots
as equivalent to 0, except that if tslots is too large it will
dereference a null pointer (CVE-2015-7799).

Add a range-check at the top of the function and make it return an
ERR_PTR() on error instead of NULL.  Change the callers accordingly.

Compile-tested only.

Reported-by: 郭永刚 <guoyonggang@360.cn>
References: http://article.gmane.org/gmane.comp.security.oss.general/17908
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust indentation]
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Reading git-format-patch failed